1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material, and more particularly to a silver halide photographic light-sensitive material containing a cyan coupler which is excellent in the dispersion stability and capable of forming well-preservable dye images.
2. Description of the Prior Art
The formation of a dye image by use of a silver halide color photographic light-sensitive material is usually carried out by the process that an aromatic primary amine-type color developing agent itself, when reducing the silver halide particles of the exposed silver halide color photographic light-sensitive material, is oxidized to produce an oxidized product, and the product then reacts with a coupler that is in advance contained in the silver halide color photographic light-sensitive material to thereby form a dye image. And, as the coupler, because color reproductions are usually effected by the subtractive color process, yellow, magenta and cyan color dyes-forming three different couplers are used.
These couplers each is usually dissolved into a substantially water-insoluble high-boiling organic solvent, if necesarry, in combination with an auxiliary solvent, and the resulting solution is then added to a silver halide emulsion.
Fundamental requirements for the nature of these couplers are such that the coupler shall have a large solubility in high-boiling organic solvents; shall have so satisfactory dispersibility and dispersion stability in a silver halide emulsion layer that it is hardly crystallized in the emulsion; shall be capable of giving satisfactory photographic characteristics; and the dye image formed from the coupler shall be highly resistant to light, heat and moisture, --especially, in the cyan coupler, the improvement on the heat resistance (dark discoloration characteristic; same meaning of dark fading properties) thereof has recently become an important question.
Those conventionally known cyan couplers include 2,5-di-acylaminophenol-type couplers which are phenol compounds substituted in the second and fifth positions thereof by acylamino radicals, as described in, e.g., U.S. Pat. No.2,895,826 and Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 112038/1975, 109630/1978 and 163537/1980.
These 2,5-diacylaminophenol-type cyan couplers are often used because they form cyan dye images satisfactory in respect of the dark-discoloration characteristic, but have the disadvantage that the dye image is very inferior in the light-discoloration characteristic.
Upon this, as means to improve the light-discoloration characteristic (same meaning of light-fading properties) of the 2,5-diacylaminophenol-type cyan coupler, the combined use therewith of benzotriazole compounds is proposed as described in, e.g., Japanese Patent O.P.I. Publication No. 151149/1975. However, such compounds are considered impractical due to the fact that they have a high tendency to crystallize and have a limited effect on the light-discoloration characteristic to ultraviolet rays alone. Further as the means there are also known the use of such conventionally used high-boiling solvents as dibutyl phthalate in an increased quantity, but the use of it in an increased quantity, although it improves the light-discoloration characteristic slightly, has an adverse effect upon the photographic characteristic such as the color tone as well as upon the dark-discoloration characteristic.
Japanese Patent O.P.I. Publication No. 173835/1982 proposes a method for improving the color tone and the fastness of the dye formed from 2,5-diacylaminophenol cyan coupler which is the phenol compound substituted in the second position thereof by orthosulfonamidophenylacylamino radical by way of dispersing the coupler into a high-boiling organic solvent having a specific dielectric constant. However, this method considerably impairs the light-discoloration characteristic of the cyan dye image.